Map sensor voltage adjust

Okay guys i have done a search and cannot find anything about this. I am working with banks to set me up with a header for my 2.5L motor. Heat and fuel mixture came up and he said he had seen a lot of cracking due to heat and the lean mixture from the map sensor on jeeps. He gave me a link which is http://www.turbocity.com/product_inf...roducts_id=415 this is suppose to fool computer into thinking it needs more gas by an adjusting the voltage from .5 volts to whatever. Not sure if its for a 4.0 or 2.5 or if it would matter. Has anyone ran one of these. I can see where a lean mix would create heat and stress the header material. Here is another link also that kinda explains it a little
http://www.angelfire.com/my/fan/MAP_adjuster.html I would like your input on this before i buy it Thank You John

Maybe i should have done this in the modified section. But we shall see.

Kragen shows the MAP sensor is the same for '86 2.5L and '87 4.0L. I don't know how long they used the sensor.